The UK Foreign Office is still urging tourists in Nigeria to be vigilant over the Easter period amid reports security services foiled a Boko Haram plot on the British and US embassies in Abuja.

"We are grateful for the support we receive from the Nigerian security authorities in protecting UK diplomatic staff and premises in Nigeria," a spokesperson for the ministry said.

"We are in regular contact with the Nigerian security authorities concerning potential threats to UK interests in Nigeria."

The statement was issued just hours after Nigeria's Department of State Services (DSS) claimed to have arrested six people from the Islamic State (Isis) linked group over the plot in March.

"The group had perfected plans to attack the UK and American Embassies and other western interests in Abuja," a DSS spokesperson told Reuters.

The UK government said there is a "high threat" of kidnap throughout Nigeria, especially in the Niger Delta region and Kogi state, whilst the most recent terrorist kidnaps have happened mostly in northern Nigeria.

"You should avoid public places where crowds gather, including religious gatherings and insecure public spaces like places of worship, markets, transport hubs and camps for displaced people. You should be particularly vigilant around the Easter period," the FCO added.

Unicef has warned that Boko Haram are increasingly using children for their terror attacks. The charity said more than 110 assaults have been conducted by youths since 2014, with the vast majority of those attacks (80%) being bombs strapped to girls.

"In the first three months of this year, the number of children used in bomb attacks is nearly the same as the whole of last year – this is the worst possible use of children in conflict," said Marie-Pierre Poirier, Unicef's regional director for West and Central Africa.

Who are Nigeria's Boko Haram terrorists?

Boko Haram, which has renamed itself Iswap, fights against Western influence in Nigeria and aims to impose its version of Sharia law throughout occupied territories.

The group launches attacks in Nigeria and neighbouring countries in a bid to take control of more territory. Three Nigerian states − Adamawa, Borno and Yobe − have been under a state of emergency since May 2013.

Boko Haram has killed more than 20,000 people since 2009 and was deemed the world's deadliest terror group, surpassing Isis in November 2015. Nigeria has also become the world's third-most terrorised country as a result of the group's violent insurgency.